The present application claims priority to Japanese Application(s) No(s). P2000-284260 filed Sep. 19, 2000, which application(s) is/are incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to a polishing method, a polishing apparatus, a plating method, and a plating apparatus used in producing a semiconductor device, more particularly relates to a polishing method and a polishing apparatus of a copper film or other film in a damascene process and a plating method and a plating apparatus used in processes of forming a copper film etc.
2. Description of the Related Art
Along with the increase in integration and reduction of size of semiconductor devices, progress has been made in miniaturization of interconnections, reduction of interconnection pitch, and superposition of interconnections. The importance of the multilayer interconnection technology in the manufacturing process of semiconductor devices is therefore rising.
On the other hand, conventionally aluminum has been frequently used as an interconnection material of a semiconductor device having a multilayer interconnection structure, but in order to suppress the propagation delay of signals in the recent 0.25 xcexcm or less design rule, an interconnection process for replacing the aluminum of the interconnection material by copper is being developed. When using copper for interconnections, there is the merit that both a low resistance and a high electromigration tolerance can be obtained.
In a process using this copper for interconnections, for example, an interconnection process referred to as the damascene process for burying a metal in a groove-like interconnection pattern formed in an interlayer insulation film in advance and removing excess metal film by chemical mechanical polishing (CMP) to form the interconnections has become dominant. The damascene process has the characteristics that etching of the interconnections become unnecessary and also a further upper interlayer insulation film becomes flat by itself, so the process can be simplified.
Further, by the dual damascene process where not only grooves for the interconnections, but also the contact holes are formed as grooves in the interlayer insulation film and where the interconnections and the contact holes are simultaneously buried by the metal, a greater reduction of the interconnection steps becomes possible.
Here, an explanation will be made of an example of the process for forming copper interconnections by the dual damascene process by referring to the figures below.
First, as shown in FIG. 34A, for example, an interlayer insulation film 302 made of for example silicon oxide is formed by for example low pressure chemical vapor deposition (CVD) on a silicon or other semiconductor substrate 301 on which a not illustrated impurity diffusion region is appropriately formed.
Next, as shown in FIG. 34B, contact holes CH communicating with the impurity diffusion region of the semiconductor substrate 301 and grooves M in which will be formed a predetermined pattern of interconnections to be electrically connected to the impurity diffusion region of the substrate 301 are formed by using well-known photolithography and etching.
Next, as shown in FIG. 34C, a barrier metal film 305 is formed on the surface of the interlayer insulation film 302 and in the contact holes CH and the grooves M. This barrier metal film 305 is formed by a material such as Ta, Ti, TaN, or TiN by well-known sputtering. When the interconnection material is copper and the interlayer insulation film 302 is silicon oxide, since copper has a large diffusion coefficient with respect to silicon oxide, it is easily oxidized. The barrier metal film 305 is provided to prevent this.
Next, as shown in FIG. 35A, a seed film 306 is formed on the barrier metal film 305 to a predetermined thickness by well-known sputtering.
Then, as shown in FIG. 35B, a copper film 307 is grown and formed on the seed film 306 so as to bury the contact holes CH and the grooves M by copper. The copper film 307 is formed by for example plating, CVD, sputtering, etc.
Next, as shown in FIG. 35C, the excess copper film 307 and barrier metal film 305 on the interlayer insulation film 302 are removed by CMP for flattening.
Due to the above steps, copper interconnections 308 and contacts 309 are formed.
By repeating the above process on the interconnections 308, multilayer interconnections can be formed.
Summarizing the problems to be solved by the invention, in the step of removing the excess copper film 307 by CMP in the copper interconnection forming process using the dual damascene process, because the flattening technique employing conventional CMP involves applying a predetermined pressure between a polishing tool and the copper film for polishing, there arises a problem that large damage is given to the semiconductor substrate.
Especially, in a case where an insulation film of a small dielectric constant, for example, a polyimide film or other organic insulation film, or an SiOF film comprised of silicon oxide including fluorine, or an inorganic insulation film such as porous silica or other gel insulation film, is used for the interlayer insulation film for the purpose of reducing the parasitic capacitance in interconnections to raise the operation speed of a semiconductor device, since generally these insulation films have low mechanical strength, the aforesaid damage in the above CMP process is no longer negligible and may cause cracks of the interlayer insulation film and separation of the interlayer insulation film from the semiconductor substrate.
Further, the removal performance differs among the interlayer insulation film 302, the copper film 307, and the barrier metal film 305, therefore there has been the problem that dishing, erosion (thinning), recesses, etc. easily occur in the interconnections 308.
Dishing is a phenomenon where, as shown in FIG. 36, when there is an interconnection 308 having a width of, for example, about 100 xcexcm at a 0.18 xcexcm design rule, the center portion of the interconnection is excessively removed and sinks. If this dishing occurs, the sectional area of the interconnection 308 becomes insufficient. This causes poor interconnection resistance etc. This dishing is apt to occur when copper or aluminum, which are relatively soft, is used as the interconnection material.
Erosion is a phenomenon where, as shown in FIG. 37, a portion having a high pattern density such as where interconnections with a width of 1.0 xcexcm are formed at a density of 50% in a range of for example 3000 xcexcm is excessively removed. When erosion occurs, the sectional area of the interconnections becomes insufficient. This causes poor interconnection resistance etc.
Recess is a phenomenon where, as shown in FIG. 38, the interconnection 308 becomes lower in level at the interface between the interlayer insulation film 302 and the interconnection 308 resulting in a step difference. In this case as well, the sectional area of the interconnection becomes insufficient, causing poor interconnection resistance etc.
Further, in the step of flattening and removing the excess copper film 307 by CMP, it is necessary to efficiently remove the copper film. The amount removed per unit time, that is, the polishing rate, is required to be for example more than 500 nm/min.
In order to obtain this polishing rate, it is necessary to increase the polishing pressure on the wafer. When the polishing pressure is raised, as shown in FIG. 39, a scratch SC and chemical damage CD are apt to occur in the interconnection surface. In particular, they easily occur in soft copper. For this reason, they cause opening of the interconnections, short-circuiting, poor interconnection resistance, and other defects. Further, if the polishing pressure is raised, there is the inconvenience that the amount of the scratches, separation of interlayer insulation film, dishing, erosion, and recesses also becomes larger.
A first object of the present invention is to provide a polishing method and a polishing apparatus capable of easily flattening an initial unevenness, excellent in efficiency of removing an excess copper film, and capable of suppressing damage to an interlayer insulation film below a copper film when flattening the copper film by polishing in a process of producing a semiconductor device having copper interconnections.
On the other hand, in the process of copper-buried electroplating, a pre-process of the above polishing process, basically it is difficult to form a film of a uniform thickness over the entire surface. In the current state, films are usually formed with a variability of thickness of about 3 to 5%. CMP processing is performed to form interconnections from this state. Even if the uniformity of the amount of removal by the CMP were 0%, in a case where CMP is performed until the excess copper on the entire surface is removed, over-polishing occurs to the extent of the variability in formation of the plating film and in turn dishing, erosion, and recess to the same extent become inevitable. For example, assuming a 10,000 xc3x85 copper film is plated to form an interconnection that is 5000 xc3x85 in depth, the variability in thickness is 3 to 5%, i.e., 300 to 500 xc3x85. A recess caused by 300 to 500 xc3x85 over-polishing corresponds to 6 to 10% loss of the sectional area with respect to a 5000 xc3x85 interconnection. This is too large to be negligible in formation of interconnections.
Therefore, to solve the above problem, a second object of the present invention is to provide a plating method and a plating apparatus able to deposit a flat copper film and applicable to a process of forming an interconnection of a semiconductor device.
To attain the first object, according to a first aspect of the present invention, there is provided a polishing method for polishing an object having a film on a surface to be polished, comprising the steps of measuring data equivalent to a thickness of the film on the object and making a relatively small cathode member compared with the surface face a region of the surface, interposing an electrolytic solution at least between that region of the surface and the cathode member, and in that state applying a voltage with the cathode member serving as a cathode and the film as an anode to electrolytically polish and flatten the film by electrolytic elution in that region of the surface preferentially from projecting portions of the film until removing a target amount of the film obtained from the thickness equivalent data; wherein the process of moving the cathode member to another region of the surface and electrolytically polishing the film in that other region until removing the target amount of film to flatten the film is repeated over the entire surface, to thereby remove the target amount of film over the entire surface.
Preferably, the film comprises a copper film.
The present polishing method preferably further comprises a step of calculating the amount of the film to be removed from the thickness equivalent data after the step of measuring the thickness equivalent data and before the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface.
Preferably, the cathode member is moved continuously from one region to another region of the surface.
More preferably, the speed of movement of the cathode member is controlled in accordance with the target amount of the film to be removed obtained from the thickness equivalent data.
Preferably, the cathode member is moved stepwise from one region to another region of the surface.
Preferably, as the thickness equivalent data of the film, the thickness of the film is measured.
Preferably, in the step of measuring the thickness equivalent data of the film, the thickness equivalent data of the film in the region where the cathode member faces the surface is measured, and the process of moving the cathode member to another region of the surface, measuring the thickness equivalent data of the film in that other region, and electrolytically polishing and flattening the film by electrolytic elution preferentially from projecting portions of the film in that other region until removing the target amount of the film obtained from the thickness equivalent data is repeated over the entire surface.
More preferably, in the step of measuring the thickness equivalent data of the film, as the thickness equivalent data of the film, an electrolytic current of the electrolytic polishing is measured in the region where the cathode member faces the surface, and in the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface, the electrolytic polishing is performed until removing the target amount of the film determined by the electrolytic current of the electrolytic polishing.
Still more preferably, in the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface, the target amount of the film remaining at the point of time when the electrolytic current of the electrolytic polishing becomes a specified value is determined to be zero and the electrolytic polishing in that region of the surface is finished.
Preferably, the cathode member is shaped so as to be able to apply a stronger electric field to a projecting portion than to a recessed portion of the film corresponding to the unevenness of the film in that region of the surface. In the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface, by applying this electric field, the film is polished electrolytically and flattened by electrolytic elution in the region of the surface preferentially from a projecting portion of the film.
More preferably, the surface has a projecting and recessed pattern formed by repeating a projecting and recessed pattern in that region of the surface. By moving the cathode member stepwise to other regions of the surface and applying the stronger electric field to the projecting portion than to the recessed portion of the film corresponding to the unevenness of the film in these other regions, the step of electrolytically polishing and flattening the film by electrolytic elution preferentially from projecting portions of the film is repeated over the entire surface.
Preferably, the cathode member is divided into a plurality of regions which are arranged insulated from each other and the cathode member as a whole faces the entire surface. By changing the position of application of voltage to the divided cathode member, the substantially equivalent is obtained as when changing the position of the cathode member facing the surface from one region to another region.
More preferably, the cathode member is divided into a plurality of concentric circular regions, and the entire surface is electrolytically polished by changing the position of application of voltage from the inner side to the outer side of the cathode member divided into concentric circular regions.
Preferably, when making a relatively small cathode member compared with the surface face that region of the surface, an anode member set apart from the cathode member at a certain distance is made to face the surface, an electrolytic solution is interposed at least between that region of the surface and the cathode member and between the surface and the anode member, and a voltage is applied to the cathode member and the anode member so as to apply the voltage de facto with the cathode member as a cathode and the surface as an anode.
More preferably, the anode member is comprised of a nobler metal than the material on the surface.
Preferably, in the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface, chemical mechanical polishing is performed at the same time as the electrolytic polishing to flatten the film by composite polishing combining the electrolytic polishing and the chemical mechanical polishing.
Preferably, when a voltage is applied with the cathode member as a cathode and the surface as an anode, a direct-current voltage is applied.
More preferably, a rectangular pulse voltage is applied.
Further, in a case where an anode member set apart from the cathode member at a certain distance is made to face the surface, when a voltage is applied to the cathode member and the anode member, preferably an alternating-current voltage is applied.
Preferably, in the step of electrolytically polishing and flattening the film by electrolytic elution in that region of the surface, an electrolytic current of the electrolytic polishing in the region is measured at the same time.
More preferably, the voltage applied with the cathode member as a cathode and the surface as an anode is controlled to maintain the electrolytic current constant.
Further, more preferably, the progress in flattening the film in that region of the surface is managed through the electrolytic current.
According to the polishing method of the present invention, data corresponding to a thickness of the film on the object is measured, a relatively small cathode member compared with the surface is made to face a region of the surface, an electrolytic solution is interposed at least between that region of the surface and the cathode member, a voltage is applied with the cathode member serving as a cathode and the film as an anode, and the film is electrolytically polished by electrolytic elution in that region of the surface preferentially from projecting portions of the film until removing the target amount of the film obtained from the thickness equivalent data to flatten the film.
Here, in order to remove the target amount of film over the entire surface, a step of moving the cathode member to other regions of the surface and the step of electrolytically polishing and flattening the film in these other regions until removing the target amount of the film are repeated over the entire surface.
According to the polishing method of the present invention, it is possible to set the distribution of the necessary amounts of removal under conditions obtained after measuring beforehand the variability of the thickness of a film plated on a surface and, in accordance with this, remove the film as necessary for formation of interconnections by polishing by exactly the right amounts.
In addition, by moving the cathode member so that the actual distribution of the amounts of removal over the entire surface, comprised of the partial amounts of removal superposed on the surface, coincides with the above preset distribution of the amounts of removal, the film can be removed as necessary for formation of interconnections by polishing by exactly the right amounts over the entire surface.
Further, since the film on the surface is removed by polishing by electrolytic elution, unlike the CMP method, it is no longer necessary to apply pressure on the film, so occurrence of cracks of the film or damage to the lower interlayer insulation film can be suppressed.
In addition, in the above removal by polishing by electrolytic elution, only the projecting portions are selectively electrolytically eluded at the uneven portions formed on the surface of the film, so effective flattening can be achieved.
As described above, according to the polishing method of the present invention, when flattening a film by polishing, initial unevenness can be easily flattened, excellent efficiency of removal of excess copper film can be obtained, and damage to a lower interlayer insulation film can be suppressed.
In addition, to achieve the first object, according to a second aspect of the present invention, there is provided a polishing method for polishing an object having a film on a surface to be polished, comprising the steps of measuring data corresponding to a thickness of the film on the object; making a relatively small cathode member compared with the surface face a region of the surface, interposing an electrolytic solution including a chelating agent at least between that region of the surface and the cathode member, and in that state applying a voltage with the cathode member serving as a cathode and the film as an anode to oxidize the surface of the film by anodic oxidation and form a chelate film of the oxidized material; and selectively removing a projecting portion of the chelate film corresponding to unevenness of the film to expose the film of the projecting portion at the surface; wherein a step of moving the cathode member from one region to an other region of the surface, the chelate film forming step, and the chelate film removing step are repeated until removing the target amount of the film determined from the thickness equivalent data over the entire surface to flatten the entire surface.
Preferably, the film comprises a copper film.
Preferably, the electrolytic solution further includes a surface-active agent.
The polishing method of the present invention preferably further comprises a step of calculating the target amount of the film to be removed from the thickness equivalent data after the step of measuring the thickness equivalent data and before the chelate film forming step in that region of the surface.
Preferably, the cathode member is moved continuously from one region to another region of the surface.
More preferably, the speed of movement of the cathode member is controlled in accordance with the target amount of the film to be removed obtained from the thickness equivalent data.
Preferably, the cathode member is moved stepwise from one region to another region of the surface.
Preferably, as the thickness equivalent data of the film, the thickness of the film is measured.
Preferably, in the step of measuring the thickness equivalent data of the film, the thickness equivalent data of the film in the region where the cathode member faces the surface is measured, and the step of moving the cathode member to other regions of the surface, the step of measuring the thickness equivalent data of the film in these other regions, the chelate film forming step, and the chelate film removing step are repeated over the entire surface.
More preferably, in the step of measuring the thickness equivalent data of the film, as the thickness equivalent data of the film, an electrolytic current of the anodic oxidation is measured in the region where the cathode member faces the surface, and the step of measuring an electrolytic current of the anodic oxidation, the chelate film forming step, and the chelate film removing step are repeated over the entire surface until removing the target amount of the film determined by the electrolytic current of the anodic oxidation.
Still more preferably, when repeating the step of measuring the electrolytic current of the anodic oxidation in a region of the surface, the chelate film forming step, and the chelate film removing step over the entire surface, the target amount of the film remaining at the point of time when the electrolytic current of the anodic oxidation becomes a specified value is determined to be zero and the chelate film forming step and the chelate film removing step in that region of the surface are finished.
Preferably, the cathode member is shaped so as to be able to apply a stronger electric field to a projecting portion than to a recessed portion of the film corresponding to the unevenness of the film in that region of the surface. In the chelate film forming step and the chelate film removing step in that region of the surface, by applying this electric field, the chelate film is formed and removed preferentially from projecting portions of the film to flatten the film.
More preferably, the surface has a projecting and recessed pattern formed by repeating a projecting and recessed pattern in that region of the surface. By moving the cathode member stepwise to other regions of the surface and applying the stronger electric field to the projecting portion than to the recessed portion of the film corresponding to the unevenness of the film in these other regions, the step of chelating the film and removing the formed chelate film preferentially from a projecting portion of the film to flatten the film is repeated over the entire surface.
Preferably, the cathode member is divided into a plurality of regions which are arranged insulated from each other and the cathode member as a whole faces the entire surface. By changing the position of application of a voltage to the divided cathode member, the substantially equivalent is obtained as when changing the position of the cathode member facing the surface from one region to another region.
More preferably, the cathode member is divided into a plurality of concentric circular regions, and the entire surface of the film is oxidized by anodic oxidation and chelated by changing the position of application of a voltage from the inner side to the outer side of the cathode member divided into concentric circular regions.
Preferably, when making a relatively small cathode member compared with the surface face that region of the surface, an anode member set apart from the cathode member at a certain distance is made to face the surface, an electrolytic solution is interposed at least between that region of the surface and the cathode member and between the surface and the anode member, and a voltage is applied to the cathode member and the anode member so as to apply the voltage de facto with the cathode member as a cathode and the surface as an anode.
More preferably, the anode member is comprised of a nobler metal than the material on the surface.
Preferably, in the step of removing the chelate film in that region of the surface, a projecting portion of the chelate film corresponding to the unevenness of the film is selectively removed by wiping.
Alternatively, preferably, in the step of removing the chelate film in that region of the surface, the chelate film is removed by applying vibration.
Alternatively, preferably, in the step of removing the chelate film in that region of the surface, the chelate film is removed by applying a jet.
Preferably, when a voltage is applied with the cathode member as a cathode and the surface as an anode, a direct-current voltage is applied.
More preferably, a rectangular pulse voltage is applied.
Further, in a case where an anode member set apart from the cathode member at a certain distance is made to face the surface, when a voltage is applied to the cathode member and the anode member, preferably an alternating-current voltage is applied.
Preferably, in the step of oxidizing the film by the anodic oxidation in that region of the surface, an electrolytic current of the anodic oxidation in the region is measured at the same time.
More preferably, the voltage applied with the cathode member as a cathode and the surface as an anode is controlled to maintain the electrolytic current constant.
Still more preferably, the progress in flattening the film in that region of the surface is managed through the electrolytic current.
According to the above polishing method of the present invention, data corresponding to a thickness of a film on an object is measured, the relatively small cathode member compared with the surface is made to face a region of the surface, an electrolytic solution including a chelating agent is interposed at least between that region of the surface and the cathode member, and the surface of the film is oxidized by anodic oxidation and a chelate film of the oxidized material is formed by applying a voltage with the cathode member serving as a cathode and the film as an anode. Further, projecting portions of the chelate film are selectively removed corresponding to unevenness of the film to expose the film of a projecting portion at its surface.
Here, the step of moving the cathode member from one region to other regions of the surface, the chelate film forming step, and the chelate film removing step are repeated until removing the target amount of film determined from the thickness equivalent data over the entire surface to flatten the entire surface.
According to the above polishing method of the present invention, the uneven surface formed on the film on the surface is partially oxidized by anodic oxidation in a region of the surface, reacts with a chelating agent supplied as a processing solution, and is chelated. Therefore, a chelate film of rather low mechanical strength able to be easily removed is formed. If removing a projecting portion of the chelate film, because the further exposed copper is chelated after being oxidized by anodic oxidation, flatness of the film is achievable by repeating the step of removing the projecting portion of the chelate film.
In addition, if a surface-active agent is added into the processing solution, the chelate film on the uneven surface is micelled forming an insoluble complex micelle, further, it can be easily and selectively removed preferentially from a projecting portion.
Within the range to which the electric action of the cathode member extends, since the electrical resistance of the chelate film is higher than copper, the copper covered by the not removed chelate film remaining in the groove is hard to be oxidized by anodic oxidation by conducting a current, so the chelation of this region is very slow and the chelate film is formed by anodic oxidation only at the projecting portion of the copper exposed by the removal of the previous chelate film.
Further, because the current is supplied through an electrolytic solution, if the potential difference between the film on the anode and the cathode member of the cathode is constant, the current density becomes larger the shorter the distance between electrodes. Therefore, in the film exposed after removing the chelate film, the more projecting a part of the film is, the shorter the electrode distance to the cathode member used as the cathode and thus the higher the current density and consequently the higher the speed of the anodic oxidation and the faster the chelation.
Further, since the volume of the chelate film formed on the uneven surface is greater than the original copper, the step difference on the uneven surface is magnified large compared with the step difference on the surface of the original copper. Therefore, the mechanical removal energy due to wiping etc. received by a projecting portion is large.
Accordingly, within the range to which the electrical action of the cathode member extends, projecting portions of the film can be removed preferentially and can be flattened effectively.
In addition, it is possible to set the distribution of the necessary amounts of removal by conditions obtained by measuring beforehand the variability of the thickness of a film plated on a surface and, in accordance with this, remove the film necessary as necessary for formation of interconnections by polishing by exactly the right amounts.
In addition, by moving the cathode member so that the actual distribution of the amounts of removal over the entire surface comprised of the partial amounts of removal superposed on the surface coincides with the above preset distribution of amounts of removal, it is possible to remove the film as necessary for formation of interconnections by polishing by exactly the right amounts over the entire surface.
Further, since the film on the surface is removed by polishing by anodic oxidation, chelation, and removal of the chelate film, unlike the CMP method, it is no longer necessary to apply pressure on the film, so occurrence of cracks of the film or damage to the lower interlayer insulation film can be suppressed.
As described above, according to the polishing method of the present invention, when flattening a film by polishing, an initial unevenness can be easily flattened, excellent efficiency of removal of excess copper film can be obtained, and damage to a lower interlayer insulation film can be suppressed.
In addition, to achieve the first object, according to a third aspect of the present invention, there is provided a polishing apparatus for polishing an object having a film on a surface to be polished, comprising a table for holding the object, a measuring means for measuring data corresponding to a thickness of the film on the object, a cathode member relatively small compared with the surface and arranged to face a region of the surface, an electrolytic solution feeding means for feeding an electrolytic solution at least between that region of the surface and the cathode member, a power supply for applying a voltage with the cathode member serving as a cathode and the film serving as an anode, a control means for controlling application of voltage until removing the target amount of film obtained from the thickness equivalent data when the film is electrolytically polished by electrolytic elution in that region of the surface, and a moving means for moving the cathode member to other regions of the surface in order to remove the target amount of film over the entire surface.
Preferably, the film comprises a copper film.
The polishing apparatus of the present invention preferably further comprises a calculating unit for calculating the target amount of the film to be removed from the thickness equivalent data.
Preferably, the measuring means measures a thickness of the film.
Preferably, the measuring means measures an electrolytic current of electrolytic polishing in a region where the cathode member faces the surface, and the control means controls a voltage to be applied until removing the target amount of film determined by the electrolytic current of the electrolytic polishing in that region of the surface.
More preferably, the control means determines the target amount of the film remaining at the point of time when the electrolytic current of the electrolytic polishing becomes a specified value to be zero and controls the electrolytic polishing in that region of the surface to finish.
Preferably, the cathode member is shaped so as to be able to apply a stronger electric field to a projecting portion than to a recessed portion of the film corresponding to the unevenness of the film in that region of the surface. By applying this electric field, the film is polished electrolytically and flattened by electrolytic elution in that region of the surface preferentially from a projecting portion of the film.
Preferably, the cathode member is divided into a plurality of regions which are arranged insulated from each other and the cathode member as a whole faces the entire surface. By changing the position of application of voltage to the divided cathode member, the substantially equivalent is obtained as when changing the position of the cathode member facing the surface from one region to another region.
More preferably, the cathode member is divided into a plurality of concentric circular regions.
The polishing apparatus of the present invention preferably further comprises an anode member facing the surface and set apart from the cathode member at a certain distance, the electrolytic feeding means feeds an electrolytic solution between the region of the surface and the cathode member and between the surface and the anode member, and the power supply applies a voltage to the cathode member and the anode member.
More preferably, the anode member is comprised of a nobler metal than the material on the surface.
The polishing apparatus of the present invention preferably further comprises a polishing means for chemical mechanical polishing and performs the chemical mechanical polishing in that region of the film at the same time as the electrolytic polishing to flatten the film.
Preferably, the power supply applies a direct-current voltage with the cathode member as a cathode and the surface as an anode.
More preferably, the power supply applies a rectangular pulse voltage.
Further, in a case where an anode member set apart from the cathode member at a certain distance is made to face the surface, preferably the power source applies an alternating-current voltage to the cathode member and the anode member.
The polishing apparatus of the present invention preferably further comprises an ammeter for measuring an electrolytic current of the electrolytic polishing in that region.
More preferably, the control means controls the voltage applied to the cathode member and the surface so as to maintain the electrolytic current constant.
According to the above polishing apparatus of the present invention, the film on the surface can be polished by the polishing method of the present invention. When flattening a film by polishing, an initial unevenness can be easily flattened, excellent efficiency of removal of an excess copper film can be obtained, and damage to a lower interlayer insulation film can be suppressed.
In addition, to achieve the above object, according to a fourth aspect of the present invention, there is provided a polishing apparatus for polishing an object having a film on a surface to be polished, comprising a table for holding the object, a measuring means for measuring data corresponding to a thickness of the film on the object, a cathode member relatively small compared with the surface and arranged to face a region of the surface, an electrolytic solution feeding means for feeding an electrolytic solution including a chelating agent at least between the region of the surface and the cathode member, a power supply for applying a voltage with the cathode member serving as a cathode and the film as an anode, a control means for controlling the application of voltage until the surface of the film is oxidized by anodic oxidation in that region of the surface and a chelate film of the oxidized material is formed, a chelate film removing means for removing the chelate film, and a moving means for moving the cathode member to other regions of the surface in order to remove a target amount of the film obtained from the thickness equivalent data over the entire surface.
Preferably, the film comprises a copper film.
Preferably, the chelate film removing means selectively removes a projecting portion of the chelate film corresponding to unevenness of the film.
Preferably, as an electrolytic solution, the electrolytic feeding means feeds an electrolytic solution further including a surface-active agent.
The polishing apparatus of the present invention preferably further comprises a calculating unit for calculating the target amount of the film to be removed from the thickness equivalent data.
Preferably, the measuring means measures a thickness of the film.
Alternatively, the measuring means measures an electrolytic current of the anodic oxidation in a region where the cathode member faces the surface, and the control means controls the voltage to be applied until removing the target amount of film determined by the electrolytic current of the anodic oxidation in that region of the surface.
More preferably, the control means determines the target amount of the film remaining at the point of time when the electrolytic current of the anodic oxidation becomes a specified value to be zero and controls the anodic oxidation in that region of the surface to finish.
Preferably, the cathode member is shaped so as to be able to apply a stronger electric field to a projecting portion than to a recessed portion of the film corresponding to the unevenness of the film in that region of the surface. By applying this electric field, the film is oxidized by anodic oxidation and chelated in that region of the surface preferentially from a projecting portion of the film to flatten the film.
Preferably, the cathode member is divided into a plurality of regions which are arranged insulated from each other and the cathode member as a whole faces the entire surface. By changing the position of application of voltage to the divided cathode member, the substantially equivalent is obtained as when changing the position of the cathode member facing the surface from one region to another region.
More preferably, the cathode member is divided into a plurality of concentric circular regions.
The polishing apparatus of the present invention preferably further comprises an anode member facing the surface and set apart from the cathode member at a certain distance, the electrolytic feeding means feeds an electrolytic solution between the region of the surface and the cathode member and between the surface and the anode member, and the power supply applies a voltage to the cathode member and the anode member.
More preferably, the anode member is comprised of a nobler metal than the material on the surface.
The polishing apparatus of the present invention preferably comprises a wiping means for selectively removing projecting portions of the chelate film corresponding to the unevenness of the film as the chelate film removing means.
Alternatively, preferably, the chelate film removing means includes a vibration applying means.
Alternatively, preferably, the chelate film removing means includes a jet generating and applying means for applying a jet to the chelate film.
Preferably, the power supply applies a direct-current voltage with the cathode member as a cathode and the surface as an anode.
More preferably, the power supply applies a rectangular pulse voltage.
Further, in a case where an anode member set apart from the cathode member at a certain distance is made to face the surface, preferably the power source applies an alternating-current voltage to the cathode member and the anode member.
The polishing apparatus of the present invention preferably further comprises an ammeter for measuring an electrolytic current of the anodic oxidation in that region.
More preferably, the control means controls the voltage applied to the cathode member and the surface so as to maintain the electrolytic current constant.
According to the above polishing apparatus of the present invention, the film on the surface can be processed by the polishing method of the present invention. When flattening a film by polishing, an initial unevenness can be easily flattened, excellent efficiency of removal of excess copper film can be obtained, and damage to a lower interlayer insulation film can be suppressed.
In addition, to achieve the second object, according to a fifth aspect of the present invention, there is provided a plating method depositing a plating film on a surface of an object, comprising the steps of measuring surface height data of the surface or thickness data of the plating film on the object and making a relatively small anode member compared with the surface face a region of the surface, applying a voltage with the anode member serving as an anode and the surface as a cathode while interposing an electrolytic plating solution at least between the region of the surface and the anode member, and depositing the plating film by plating in that region of the surface until depositing a target amount of the plating film deduced from the surface height data or the thickness data of the plating film at the time of the measurement; wherein the process of moving the anode member to another region of the surface and depositing a plating film by plating in that other region is repeated over the entire surface.
Preferably, the plating film comprises a copper film.
According to the plating method of the present invention, it is possible to set a distribution of the necessary amounts of deposition under conditions obtained by measuring beforehand the surface height of a surface to be plated or by measuring plating thickness data while plating and in accordance with this form the necessary plating film by exactly the right amounts.
In addition, by moving the anode member so that the actual distribution of the amounts of deposition over the entire surface, comprised of the partial amounts of deposition superposed on the surface, coincides with the above preset distribution of the amounts of deposition, the plating film can be form by exactly the right amounts over the entire surface.
As described above, in the process of forming interconnections of a semiconductor device, a flat plating film can be deposited.
In addition, to achieve the second object, according to a sixth aspect of the present invention, there is provided a plating apparatus for depositing a plating film on a surface of an object, comprising a table for holding the object, a measuring means for measuring surface height data of the surface or plating thickness data of the plating film on the object, an anode member relatively small compared with the surface and arranged to face a region of the surface, an electrolytic plating solution feeding means for feeding an electrolytic plating solution at least between that region of the surface and the anode member, a power supply for applying a voltage with the anode member serving as an anode and the surface as a cathode, a control means for controlling application of voltage until forming by plating a target amount of the plating film deduced from the surface height data or the plating thickness data at the time of the measurement in that region of the surface, and a moving means for moving the anode member to other regions of the surface.
Preferably, the plating film comprises a copper film.
According to the plating apparatus of the present invention, it is possible to set the distribution of amounts of deposition required under conditions obtained by measuring the surface height of the surface to be plated beforehand or measuring the plating thickness data while plating and in accordance with this form the necessary plating film by exactly the right amounts.
Further, by moving the anode member so that the actual distribution of the amounts of deposition over the entire surface comprised of the partial amounts of deposition superposed on the surface coincides with the above preset distribution of amounts of deposition, it is possible to form a plating film by exactly the right amounts over the entire surface.
As described above, in the process of forming interconnections of a semiconductor device, a flat plating film can be deposited.